Pieces, square feet and loads
Blocks sell by the piece, pavers by the square foot with a known piece count per square foot, and delivery is counted in loads. Holding the conversion on the item means you quote in whichever unit the customer uses while stock stays in one consistent measure. Stating the piece count on the bill is what prevents the argument when a load is counted at the site.
Production feeding stock
A manufacturing unit adds to stock by producing rather than by purchasing, and if that entry is skipped the figure drifts immediately. Recording each day's production against the item keeps the closing figure honest and gives you a production record to read against sales — which is how you find out whether you are making the sizes that actually move.
Curing time is real stock that cannot be sold
Blocks and pavers need curing before despatch, so a portion of what exists physically is not sellable today. Treating cured and uncured as separate stock, or simply recording production dates, is what stops you promising a load that cannot leave. It is the commonest cause of a broken delivery promise in this trade.
Freight and contractor credit
Loads go to sites at distances that change the delivered price substantially, so material and freight belong on separate lines — your rate stays comparable and you can see whether the delivery is paying. The buyer is usually a contractor settling after his own payment, which makes a credit limit set in advance and monthly statements the two things that keep the account inside reach.